You will find that the appearance of the blade changes over time. Don't worry, the patina that forms is a normal reaction between the carbon steel and the air, as well as the properties of the food you cut. Your knife’s unique patina gives it a little character and some protection.
Make an effort to wash your knife straight after using it (by hand - not in the dishwasher!) and dry it immediately. Don't leave it on the draining board overnight. This risks the knife starting to rust. Your knife will not be damaged by rust spots as long as you gently scrub them off.
A knife is a cook's single most important tool. It should be treated with care. Carbon steel won't let you get lazy, because it insists on being treated right. It's a self-respecting metal like that. In return, it gives you one of the sharpest, hardest edges you could ever hope for.
Maintenance of your knives
High carbon steel will require extra care and attention, but the additional care is minimal if a routine is followed.
- Wash and completely dry the knife after each use.
- If rust does occur, remove from the blade using products like rust eraser.
- After removing rust, treat the blade with camellia oil.
Let a patina form naturally. As well as patina acting as a moderate protective layer, an established patina will prevent the iron atoms in the steel from reacting with food. Therefore, cleaning the patina off the blade is counterproductive - not to mention labour intensive.
Sharpening your knife on a regular basis will keep the edge in great condition.
To get the ultimate edge on your knives, you are going to have to invest a little time in maintenance. Using a set of whetstones will get you the best result.
To sharpen MY knives, this is the progression I personally use:
I usually finish the edge with a natural stone like the Aizu but that's optional. The leather strop with some diamond spray 0.5 micron will help you to remove the rest of the burr.
This is an enjoyable part of owning and working with Japanese knives, and the satisfaction from a job well done is worth the effort. It's not as hard as you might think!